Participants with low birth weight—especially those exposed to maternal smoking—are at an elevated risk of developing chronic obstructive pulmonary disease in adulthood, according to a large cohort study.

Researchers used UK Biobank data from 251,172 participants aged 40 to 69 years who were free of COPD at baseline. Chronic obstructive pulmonary disease (COPD) diagnoses were identified using ICD-10 codes (J40–J44) from linked electronic health records. Self-reported birth weight was categorized into quintiles, with the third quintile (Q3, median 3.32 kg) serving as the reference. The study, published in BMJ Open Respiratory Research, aimed to investigate birth weight as a potential risk factor for COPD and explore interactions with early-life exposures such as maternal smoking.

Over a median follow-up of 12.3 years, 5,602 participants developed COPD. The lowest birth weight quintile (Q1, <2.86 kg) was associated with a 21% higher COPD risk compared to Q3 (HR=1.21, 95% CI 1.11–1.32). A non-linear relationship emerged, with risk initially decreasing as birth weight increased but rising again in the highest quintile (Q5, HR=1.05, 95% CI 0.96–1.15). Stratified analyses showed that the association was most pronounced in participants exposed to maternal smoking, with significant interaction effects (P<0.05).

Sensitivity analyses, excluding participants with baseline asthma or poor self-rated health, supported the robustness of the findings. The study also considered other early-life exposures, such as breastfeeding and multiple births, though these were not significantly associated with COPD risk.

The authors noted potential limitations, including reliance on self-reported birth weight and residual confounding. Nonetheless, the findings suggest that prenatal exposures, particularly maternal smoking and low birth weight, may play a role in adult respiratory health and COPD risk.

Full disclosures can be found in the published study.